The present invention relates to a process for regenerating a catalyst. The invention especially relates to a process for regenerating a catalyst in situ in a reactor tube. Furthermore, the invention relates to a process for ex situ regeneration of a catalyst. The catalyst is suitable for use in producing normally gaseous, normally liquid and optionally normally solid hydrocarbons from synthesis gas generally provided from a hydrocarbonaceous feed, for example a Fischer-Tropsch process. The invention further relates to the regenerated catalyst and the use thereof in Fischer-Tropsch processes.
The Fischer-Tropsch process can be used for the conversion of synthesis gas (from hydrocarbonaceous feed stocks) into liquid and/or solid hydrocarbons. Generally, the feed stock (e.g. natural gas, associated gas and/or coal-bed methane, heavy and/or residual oil fractions, coal, biomass) is converted in a first step into a mixture of hydrogen and carbon monoxide (this mixture is often referred to as synthesis gas or syngas). The synthesis gas is then fed into a reactor where it is converted in one or more steps over a suitable catalyst at elevated temperature and pressure into paraffinic compounds and water. The obtained paraffinic compounds range from methane to high molecular weight hydrocarbons. The obtained high molecular weight hydrocarbons can comprise up to 200 carbon atoms, or, under particular circumstances, even more carbon atoms.
Numerous types of reactor systems have been developed for carrying out the Fischer-Tropsch reaction. For example, Fischer-Tropsch reactor systems include fixed bed reactors, especially multi-tubular fixed bed reactors, fluidised bed reactors, such as entrained fluidised bed reactors and fixed fluidised bed reactors, and slurry bed reactors such as three-phase slurry bubble columns and ebulated bed reactors.
Catalysts used in the Fischer-Tropsch synthesis often comprise a carrier based support material and one or more metals from Group 8-10 of the Periodic Table, especially from the cobalt or iron groups, optionally in combination with one or more metal oxides and/or metals as promoters selected from zirconium, titanium, chromium, vanadium and manganese, especially manganese. Such catalysts are known in the art and have been described for example, in the specifications of WO 9700231A and U.S. Pat. No. 4,595,703.
One of the limitations of a Fischer-Tropsch process is that the activity of the catalyst will, due to a number of factors, decrease over time. A catalyst that shows a decreased activity after use in a Fischer-Tropsch process is sometimes referred to as deactivated catalyst, even though it usually still shows activity. Sometimes such a catalyst is referred to as a deteriorated catalyst. Sometimes it is possible to regenerate the catalyst. This may be performed, for example, with one or more oxidation and/or reduction steps.
It is one object of the present invention to provide an in situ process for regenerating a Fischer-Tropsch catalyst comprising cobalt in a reactor tube.
It is another object of the present invention to provide an ex situ process for regenerating a Fischer-Tropsch catalyst comprising cobalt. In the ex situ process the catalyst is subjected to an ex situ treatment step. The deactivated catalyst particle(s) is/are subjected to a treatment step after being unloaded from the reactor in which the catalyst particle(s) were deactivated by use in a Fischer-Tropsch process.
Highly suitable in situ and ex situ regeneration processes for cobalt comprising catalysts are described in WO2010069978 and in PCT/EP2010/069717.
The present invention especially relates to processes in which the loss of cobalt is further minimized as compared to the processes described in WO2010069978 and PCT/EP2010/069717.